class Solution {
    public boolean isValid(String s) {
        Stack<Character> stack=new Stack<>();
        for(int i=0;i<s.length();i++){
            char ch=s.charAt(i);
            if(ch=='('||ch=='['||ch=='{'){
                stack.push(ch);
            }else{
                if(stack.empty()){
                    return false;
                }
                char top=stack.peek();
                if(top=='('&&ch==')'||top=='['&&ch==']'||top=='{'&&ch=='}'){
                    stack.pop();
                }else{
                    return false;
                }
            }
        }
        if(!stack.empty())
            return false;
        return true;
    }
}